Newly developed ferrite-resin composite materials have high rigidity (E = 1.8 × 109 N/m2) and high mechanical damping constant (in a logarithmic decrement, Δ = 1.1). The composite materials were used effectively for loudspeaker enclosure humming suppression. It is also convenient to use the composite materials in a paste state. They were applied to a hopper and a machine base for vibration control.